Description ADULT Pale morph has blue-gray upper wings, back, and tail. Head and underparts are white. Note dark smudge around eye. Dark morph is variably dark blue-gray, uniform in color, except for paler primaries. JUVENILE Similar to the adult, once chick's fluffy white down has been lost.

Dimensions Length: 18" (46 cm)

Habitat Common and found year-round in Arctic and sub-Arctic waters. Nests on ledges on sea cliffs and locally forms sizeable colonies on sea cliffs. In winter, range extends south down Atlantic seaboard.

Observation Tips Seen on pelagic trips, but also occasionally from headlands, especially during onshore gales. Many sub-Arctic birds linger in vicinity of nesting colonies throughout year.

Voice Utters various gurgling cackles and grunts at colonies, but otherwise silent.

Discussion Medium-sized, superficially gull-like sea_bird relative of shearwaters and petrels. Easily distinguished from gulls at close range by its long tubular nostrils and, in flight, by its more stiffly held wings and effortless gliding. Exceptionally buoyant, rides very high on water, and often gathers in groups where feeding is good, for example around fishing boats. Generally sociable and nests in loose colonies on sea cliffs. At nest, may regurgitate oily and smelly crop contents in a projectile fashion if alarmed by an intruder. Sexes are not separable, but different color morphs occur.